A device of this type has become known from the DE journal Drager-Rohrchen-Handbook[Drager Tube Handbook], 1994, 9th edition, p. 89, as the "Drager Tube Benzene 2/a." The selective detection of benzene in a benzene/toluene/xylene mixture is possible with such a device. The sample gas flow is fed through a prefilter into a display unit by means of a pump. Toluene and xylene react chemically with the filling in the prefilter and they are bound. The benzene component is detected in the display unit.
At least the display unit must be replaced after each measurement in the prior-art device.